import java.util.List;
import java.util.Stack;
   
/**
 * @Author 12629
 * @Description：
 */
public class MySingleList {
    static class ListNode {
        public int val;//节点的值域
        public ListNode next;//下一个节点的地址

        public ListNode(int val) {
            this.val = val;
        }

    }


    public ListNode head;//表示当前链表的头节点

    public void createList() {

        ListNode node1 = new ListNode(12);
        ListNode node2 = new ListNode(23);
        ListNode node3 = new ListNode(34);
        ListNode node4 = new ListNode(45);
        ListNode node5 = new ListNode(56);

        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;

        this.head = node1;

    }

    public void display() {
        ListNode cur = head;
        while (cur != null) {
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    }

    /**
     * 从指定位置 开始打印
     * @param newHead
     */
    public void display(ListNode newHead) {
        ListNode cur = newHead;
        while (cur != null) {
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    }

    //得到单链表的长度
    public int size() {
        int count = 0;
        ListNode = cur = head;
        while (cur != null) {
            count++;
            cur = cur.next;
        }
        return count;
    }


    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key) {
        ListNode cur = head;
        while (cur != null); {
            if (cur.val == key) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }




    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        node.next = head;
        head = node;
    }


    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        ListNode cur = head;
        if(cur == null) {
            head = node;
            return;
        }
        //找到链表的尾巴  注意是cur.next 不是cur
        while (cur.next != null) {
            cur = cur.next;
        }
        cur.next = node;
    }

    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        if(index < 0 || index > size()) {
            System.out.println("index 不合法");
            return;
        }
        if(index == 0) {
            addFirst(data);
            return;
        }
        if(index == size()) {
            addLast(data);
            return;
        }
        ListNode cur = findIndexSubOne(index);
        ListNode node = new ListNode(data);
        node.next = cur.next;
        cur.next = node;
    }

    /**
     * 找到要删除节点位置的前一个节点
     * @param index
     * @return
     */

